Z86E6116PSC Datasheet, PDF (26/69 Pages) Zilog, Inc. – Z86E61/Z86E63 CMOS Z8 16K/32K EPROM Microcontroller

Z86E61/E63
CMOS Z8 16K/32K EPROM Microcontroller
22
r7 r6 r5 r4
r3 r2 r1 r0
R253
(Register Pointer)
The upper nibble of the register file address
provided by the register pointer specifies
the active working-register group.
FF
R15 to R0
F0
Specified Working
Register Group
2F
20
1F
Register Group 1
10
0F
Register Group 0
I/O Ports
00
The lower nibble of the register file
address provided by the instruction
points to the specified register.
R15 to R0
R15 to R4
R3 to R0
Figure 14. Register Pointer
FUNCTIONAL DESCRIPTION
Counter/Timers
There are two 8-bit programmable counter/timers (T0-T1), each driven by its own
6-bit programmable prescaler. The T1 prescaler is driven by internal or external
clock sources; however, the TO prescaler is driven by the internal clock only (Fig-
ure 15).
The 6-bit prescalers can divide the input frequency of the clock source by any
integer number from 1 to 64. Each prescaler drives its counter, which decrements
the value (1 to 256) that has been loaded into the counter. When both the
counters and prescalers reach the end of the count, a timer interrupt request,
IRQ4 (T0) or IRQ5 (T1), is generated.
The counter is programmed to start, stop, restart to continue, or restart from the
initial value. The counters can also be programmed to stop upon reaching zero
PS014401-1001